Wireless communications and wireless communication devices are at the center of many important technological advancements. As the proliferation of these wireless devices increases, the efficiency and accuracy of the communications therebetween becomes vital to the commercial success of particular devices and particular communication protocols. One protocol that is showing great promise is Bluetooth, (The Specification of the Bluetooth System, v1.0 B, Dec. 1, 1999 is incorporated herein by reference) which is a wireless protocol that describes how mobile phones, computers, PDAs, peripherals and other devices can interconnect using short-range wireless connections.
To implement Bluetooth and other such wireless protocols, a device receiving a transmitted signal is required to recover bit patterns carried by the transmitted signal. This recovery process involves waveform demodulation, DC compensation, bit synchronization and bit detection. Waveform demodulation usually is implemented in a radio module and is wireless protocol dependent.
DC compensation typically involves correcting for a DC offset arising during the signal recovery process. This DC offset comprises a variation in the intended DC voltage of the recovered baseline signal caused, for example, by frequency drift in the received Bluetooth signal. Present devices compensate for DC-related imperfections in incoming signals using a variety of means, none of which are completely satisfactory. For example, certain electronic devices use analog components to calculate and track DC offset, while others use digital components. In this regard analog “DC trackers” usually are implemented as lowpass RC filters, while conventional digital approaches generally require a select number of bits to be buffered before any DC offset can be calculated.
The accuracy of the DC tracking performed by both conventional analog and digital circuits is affected by characteristics of the incoming bit patterns. For instance, when a string of high values, e.g., “1s,” is received, the computed DC offset will be adjusted to a higher value even though the actual DC offset has not changed. This is because most approaches to DC tracking automatically assume an even distribution of high and low values in the received signal. In addition, in analog approaches the accuracy of DC tracking and of the associated estimated variance are sensitive to the selected time constants of the analog filters employed. In conventional digital DC tracking techniques, the accuracy of DC tracking and of the associated estimated variance are functions of the selected buffer size.
Present technology suffers drawbacks in addition to those described above. For example, wireless devices generally must also compensate for clock variances and relative transmitter-receiver clock drift that case data frames to be out of synchronization. Present systems for synchronizing frames are slow, require significant hardware, and are not entirely accurate. Accordingly, present systems can waste valuable time and unnecessarily drop frames.
Although present analog and digital approaches to computing DC offsets and synchronizing frames for wireless communications are functional, they are not sufficiently accurate or otherwise satisfactory. Accordingly, a system and method are needed to address the shortfalls of present technology and to provide other new and innovative features.